Thor

Thor is the friend from the stars. Supreme Commander of the Asgard fleet, this small gray being with an oversized head belongs to one of the most advanced races in the universe. And for reasons that escape many, he has decided that Earth and its people are worth protecting.

When SG-1 meets the Asgard, Earth discovers it has powerful allies. Thor quickly becomes their main point of contact: he's the one they call when all seems lost, the one whose ship appears at the last second to snatch the team from certain death.

But Thor is no mere convenient savior. His people are waging a desperate war, at the other end of the universe, against the Replicators, and the Asgard, who have been cloning themselves for generations, are afflicted by a slow degeneration. Thor even sees humanity, young and full of potential, as a hope for the future of his own race.

From one rescue to the next, he becomes one of the most endearing characters in the saga: an all-powerful alien, but with a deadpan sense of humor and a genuine affection for these humans he has learned to respect. The tragic fate of the Asgard will leave a lasting mark on the Stargate program.

Here's a bit of trivia fans love: in the original version, Thor's voice belongs to Michael Shanks, the actor who also plays Daniel Jackson. He lends his voice to the Asgard commander from the second season on, so that the same actor brings to life two of the show's most beloved figures, one human and one alien.

Thor himself isn't an actor in a costume but an animated puppet, brought fully to life by a voice. That blend of technology and vocal performance made him one of the most successful non-human characters in science fiction television.